To study the effect of basalt fiber on the piping restraint of cohesionless gap-graded soils, indoor tests were conducted on discontinuous graded soil containing basalt fibers to investigate the inhibi-tory effects of fiber content, fiber length, and soil prevention location on the occurrence and development of subsurface erosion. The results indicate that the addition of basalt fibers makes the migration channels inside the soil more tortuous and narrower, thereby suppressing the growth of soil piping; When the fiber content is low, the control effect of the entire soil is better than that of only the overlying soil. As the fiber content increases, the control effect of the overlying soil is close to that of the entire soil control; When the fiber length is 15 mm, the containment effect of all soil prevention is better than that of overlying soil prevention by the greatest extent. When the fiber length is 10 mm, the difference between the two is not significant.